Joe's Fresh Guide to Sick Plant Diagnosis

[stihgnobevoli]

oh ok, i was saying it looks like iron because its mostly on the young leaves and iron is immobile and potassium is mobile. .

 

[rives]

I've missed this thread up until now - very nice work Joe. It looks like you've compiled a whole bunch of my bookmarks here! Thank you.

 

[jacksprout]

awesome guide joe

 

[Numenor]

great stuff, thanks for putting this together

 

[Rolldaddy]

Thanks...

Very informative

 

[_Dude]

Potassium deficiency? Neb is supposed to be a very heavy drinker and I was backing off the nutes because didn't know that until recently and I thought I might be burning them. I have them dropped down to 950-1000 PPMs (.7 Conversion factor I think). Should I bump them back up to 1100 or so? If nobody tells me this is definitely a deficiency I'm going to wait until my next crop goes in and keep one res at 950-1000 and bump the other one up to 1100-1200 and see which one responds better.

 

[joe fresh]

nahh the burnt tips along withh the scorching is def nute burn....give them a flush(or plain water if in hydro.dwc) for a day or 2 and then resume...

 

[_Dude]

Okay, great, glad I asked. I'm at around 950 now. What should I shoot for after the flush? 800 or so?

I'm using well water, it's 250 PPM out of the tap. And I'm running ebb and flow in hydroton/red lava rock mix.

 

[_Dude]

Used to be able to delete posts.

 

[joe fresh]

how old? how big are they? what nutes?

 

[_Dude]

They veg for 30 days in 3" net cups under a 250w MH, then 30 more in 1 gallon grow bags under a 400w MH. But they're fairly short when they go in. I top them a lot during veg. At start of flower they have 3 to 5 main stems average, and they're about 10" tall, maybe. They usually stretch to like 18" or so on average. Roughly 10" square for each plant.

I feed them straight GH Maxibloom, dry chemical nutes.

Oh yeah, the leaf I showed you is 41 days in, but I have 4 grows going on 2 reservoirs (one's empty, the other two are at 14 and 17 days).

 

[joe fresh]

then yes i would say en ec of 1.6 is a good place to start after flush, see how they like it and go from there

 

[_Dude]

Now I'm confused. Isn't 1.5 EC the same thing as 1000 PPMs using a .7 conversion factor? If so, I'm already feeding at 1.5 EC, or just below (I just re-checked to make sure my pen is set at .7 conversion factor - it is).

 

[joe fresh]

the question is did you flush?

because if you just lowered the nutes then that wont do shit....you plant is still hurtin....flush thoroughly, then start feed at 1.6 ec and go from there, your plant will tell you if thats too much or not

 

[_Dude]

Yes, I dumped both reservoirs and replaced with plain water within an hour of your recommendation. More info, both reservoirs are 55 gallon drums and I change them out every 15 days.

But if EC 1.6 is a standard feeding concentration, and amounts to 1120 PPM at .7 conversion factor, and I was already feeding at 950 at .7 conversion factor, which is well below 1120, and the plants were burning...

You see where I'm going with this, right? And Neb is universally characterized as a heavy feeder. Everybody says it needs lots of nutes.

Something's wrong with this picture, no?

then start feed at 1.6 ec and go from there, your plant will tell you if thats too much or not

As long as I'm doing my conversion math correctly, it's clearly too much. Or it's not nute burn I'm dealing with.

 

[joe fresh]

well your the one there, you can see the plant and how it does with the nutes...so listen to the plant, drop it down to 1.2 ec if you really need to and work it up from there...

but just a question on ph....your in a recirc system, over the 2 weeks does your ph got up or down? and how fast?


ill tell you right now im a dirt guy and not used to hydro, but i do know enough, but if you want expert hydro help i would ask DHF or hydro-soil...these guys are well enough experienced with hydro they could maybe help you out a bit better with your system

 

[_Dude]

I stopped measuring my PH a long time ago. I could never move it enough to make any real difference, so I just stopped keeping track. If memory serves, no, it doesn't move much. I think it stays mostly around 6.0-6.5. But I guess I can whip my PH pen out and check.

 

[joedogsong]

Yo Dude, Not keeping close track of your ph is a cardinal sin. Even the really good meters need to be calibrated on a regular basis. I've had a number of good meters and they all needed regular calibration or the plants would suffer d/t unstable fluctuations.
Just Saying you could be chasing ghosts...

 

[stihgnobevoli]

Potassium deficiency? Neb is supposed to be a very heavy drinker and I was backing off the nutes because didn't know that until recently and I thought I might be burning them. I have them dropped down to 950-1000 PPMs (.7 Conversion factor I think). Should I bump them back up to 1100 or so? If nobody tells me this is definitely a deficiency I'm going to wait until my next crop goes in and keep one res at 950-1000 and bump the other one up to 1100-1200 and see which one responds better.

def K, might be adding too much nutes locking it out.

 

[Maj.Cottonmouth]

Want take a stab at this one Joe? I am afraid of what I think it is. This is a cloned top in straight coco, mother did not/does not show this. Watered daily to runoff using tap water, Silica Blast, MaxiBloom powder at 7g per gallon, Drip Clean and pH Up.